1. Field of the Invention
The present invention relates to substrate surface treating apparatus and substrate surface treating methods for cleaning, etching, peeling or otherwise treating surfaces of glass substrates for liquid crystal displays, reticles, masks, semiconductor wafers and the like (hereinafter referred to simply as "substrates"). More particularly, the invention relates to substrate surface treating apparatus and substrate surface treating methods for providing surface treatment for a plurality of substrates stored in a cassette.
2. Description of the Related Art
A substrate manufacturing process includes a plurality of surface treatments such as photoresist application, pattern printing, development, etching, cleaning and peeling. Each of these surface treatments is carried out by a separate and individual surface treating apparatus (e.g. an exposure apparatus for pattern printing, and a cleaning apparatus for cleaning).
Each surface treatment may be carried out in a piecemeal process or a batch process, depending on the type of treatment. In the piecemeal process, surface treatment is given to one substrate after another. In the batch process, surface treatment is given simultaneously to a plurality of substrates stored in a cassette.
Each surface treating apparatus is constructed according to the type of process it carries out; piecemeal process or batch process.
A prior substrate surface treating apparatus for carrying out a predetermined surface treatment (in a batch process) of a plurality of substrates stored in a cassette has been proposed by the inventor herein as disclosed in pending Japanese Utility Model Publication No. 1989-80934.
Apparatus constructed according to the instant invention has cassettes for exclusive use in transport, and cassettes for exclusive use in treatment. Each cassette for use in transport stores a plurality of substrates, and transports these substrates between this surface treating apparatus and other surface treating apparatus. Each cassette for use in treatment stores the plurality of substrates, and supports these substrates during a surface treatment given in this apparatus. First, a transport cassette storing a plurality of substrates to be treated by this apparatus is introduced into this apparatus. The substrates to be treated are transferred from the transport cassette to a treatment or processing cassette. Next, the plurality of substrates undergo treatment along with the processing cassette storing the substrates. Upon completion of the treatment, the substrates are transported from the processing cassette to either transport cassette that brought the substrates to this apparatus or to another identical transport cassette. The transport cassette storing the plurality of treated substrates is then removed from this apparatus.
According to the prior apparatus noted above, a plurality of substrates are arranged with the same spacing (i.e. storage spacing) therebetween in the processing cassette as in the transport cassette. Such an arrangement results in the following inconveniences.
In storing a plurality of substrates in a processing cassette and providing surface treatment for these substrates en bloc, it is desirable to arrange the substrates with minimum spacing, to the extent of retaining the effect of surface treatment. This will realize a small processing space in a surface treating section, and hence a small installation space of the apparatus. Thus, the processing cassettes should desirably be constructed to store substrates with optimal spacing therebetween.
However, the optimal storage spacing for substrates in the processing cassettes is not necessarily optimal storage spacing for substrates in the transport cassettes. In the prior apparatus described above, the storage spacing of the processing cassettes is governed by that of the transport cassettes. Substrates cannot be arranged with the optimal storage spacing to receive surface treatment. Consequently, if the storage spacing of the transport cassettes is larger than the optimal spacing of the processing cassettes, for example, the entire apparatus will require a large area for installation. If the storage spacing of the transport cassettes is smaller than the optimal spacing of the processing cassettes, the effect of surface treatment could diminish.
Moreover, optimal spacing is variable with the type of surface treatment, the type and size of substrates, and so on. With the prior apparatus, therefore, optimal spacing cannot be secured for all or most of the surface treatments executed in a substrate manufacturing process. Lowering the effect of each surface treatment is impermissible from the point of view of quality control. Consequently, a spacing is determined for all of the cassettes to comply with the surface treatment required for the substrate requiring the largest storage spacing. This results in the disadvantage of enlarging not only the cassettes but various surface treating baths, whereby the entire substrate surface treating apparatus requires a large area for installation.
The surface treating section of the prior apparatus includes a transport device for transporting the processing cassettes in one direction (i.e. linearly). Thus, the treating baths constituting the treating section are arranged linearly, thereby elongating the apparatus sideways to lower efficiency of floor area utilization. Such a construction must provide maintenance areas along the respective treating baths, which enlarge the entire apparatus.
Further, the prior apparatus includes storage shelves for depositing the transport cassettes and processing cassettes. The cassettes are selectively deposited on the shelves and retrieved therefrom in accordance with the progress of treatment. However, this construction complicates the treating process, and requires an elaborate mechanism for depositing the cassettes on the shelves and retrieving the cassettes therefrom.